Usage
- Levobunolol is prescribed for the reduction of intraocular pressure (IOP) in patients with chronic open-angle glaucoma or ocular hypertension.
- Pharmacological Classification: Non-selective beta-adrenergic receptor antagonist (beta-blocker).
- Mechanism of Action: Levobunolol diminishes the production of aqueous humor, the fluid that fills the front part of the eye. While the exact mechanism is not fully understood, it’s believed to involve blocking catecholamine-stimulated increases in cyclic adenosine monophosphate (cAMP) within the ciliary processes. This, in turn, lowers IOP.
Alternate Names
- Levobunolol hydrochloride
- Brand Names: Betagan, AKBeta
How It Works
- Pharmacodynamics: Levobunolol primarily lowers IOP. It has minimal effect on pupil size or accommodation. Systemically, it can exert beta-blocking effects on the heart and lungs if absorbed.
- Pharmacokinetics: Levobunolol is administered topically as eye drops. A small amount is absorbed systemically through the conjunctiva and nasal mucosa. It is metabolized in the liver and eliminated primarily through hepatic excretion. The elimination half-life is approximately 20 hours.
- Mode of Action: Levobunolol blocks beta-1 and beta-2 adrenergic receptors in the ciliary body, reducing aqueous humor production.
- Elimination Pathways: Primarily hepatic metabolism and excretion.
Dosage
Standard Dosage
Adults:
- 0.25% solution: 1-2 drops in the affected eye(s) twice daily.
- 0.5% solution: 1-2 drops in the affected eye(s) once daily. May increase to twice daily if needed. Doses above one drop twice daily are not usually more effective.
Children:
Safety and efficacy have not been established in pediatric patients.
Special Cases:
- Elderly Patients: No specific dosage adjustments are typically required. Monitor for potential systemic effects.
- Patients with Renal Impairment: Dose adjustments may be necessary. Close monitoring is recommended.
- Patients with Hepatic Dysfunction: Dose adjustments may be necessary due to the primary hepatic metabolism of levobunolol. Close monitoring is recommended.
- Patients with Comorbid Conditions: Use with caution in patients with diabetes, cardiovascular disease, respiratory disease (especially asthma or COPD), myasthenia gravis, or hyperthyroidism.
Clinical Use Cases
The primary clinical use case is for the long-term management of chronic open-angle glaucoma and ocular hypertension. It is not typically used in emergency or acute settings like intubation, surgery, mechanical ventilation, or ICU care.
Dosage Adjustments
Adjustments may be necessary based on individual patient response and tolerance, as well as the presence of renal or hepatic dysfunction, or other comorbid conditions.
Side Effects
Common Side Effects:
- Transient burning or stinging of the eye
- Itchy or red eyes
- Eye discomfort
- Headache
- Dizziness
- Blurred vision
- Swollen eyelids
Rare but Serious Side Effects:
- Bradycardia
- Hypotension
- Bronchospasm (especially in patients with asthma or COPD)
- Heart failure
- Worsening of myasthenia gravis symptoms
- Severe allergic reactions
- Choroidal detachment (after filtration procedures)
Long-Term Effects:
With prolonged use, systemic effects like bradycardia and hypotension may occur. Regular monitoring is necessary.
Adverse Drug Reactions (ADR):
- Severe bradycardia, heart block, or hypotension requiring intervention.
- Bronchospasm requiring respiratory support.
Contraindications
- Bronchial asthma or history of asthma
- Severe chronic obstructive pulmonary disease (COPD)
- Sinus bradycardia
- Second or third-degree atrioventricular block
- Overt cardiac failure
- Cardiogenic shock
- Hypersensitivity to any component of the product
Drug Interactions
- Oral beta-blockers (e.g., atenolol, metoprolol): Additive effects leading to bradycardia and hypotension.
- Calcium channel blockers (e.g., nifedipine): Increased risk of hypotension and bradycardia.
- Digoxin: Additive bradycardic effects.
- Other beta-blocker eye drops (e.g., timolol, betaxolol): Additive effects on IOP and systemic beta-blockade.
- Reserpine: Increased risk of bradycardia and hypotension.
- Insulin or oral diabetes medications: May mask signs of hypoglycemia.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (US FDA classification - As of 2017. There may be an update on this. Consult updated resources.)
- Fetal risks are not fully known. Use only if potential benefit outweighs potential risk.
- Excretion in breast milk: Unknown. Systemic beta-blockers are excreted in breast milk. Exercise caution.
Drug Profile Summary
- Mechanism of Action: Reduces aqueous humor production by blocking beta-adrenergic receptors in the ciliary body.
- Side Effects: Burning/stinging, itching, blurred vision, bradycardia, hypotension, bronchospasm.
- Contraindications: Asthma, COPD, severe bradycardia, heart block, cardiac failure.
- Drug Interactions: Oral beta-blockers, calcium channel blockers, digoxin.
- Pregnancy & Breastfeeding: Use with caution. Potential risks to the fetus and nursing infant.
- Dosage: 0.25% - 1-2 drops BID; 0.5% - 1-2 drops daily or BID.
- Monitoring Parameters: IOP, heart rate, blood pressure, respiratory function.
Popular Combinations
Levobunolol is sometimes used in combination with other IOP-lowering medications like prostaglandin analogs (e.g., latanoprost) or carbonic anhydrase inhibitors (e.g., dorzolamide) when monotherapy is insufficient.
Precautions
- General Precautions: Monitor for systemic effects, especially in patients with cardiovascular or respiratory disease.
- Specific Populations: As mentioned in the Special Cases section of Dosage.
- Lifestyle Considerations: May cause blurred vision or dizziness. Advise patients to use caution when driving or operating machinery.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Levobunolol?
A: Adults: 0.25% solution: 1-2 drops BID; 0.5% solution: 1-2 drops daily or BID. Pediatric use is not recommended.
Q2: What are the common side effects of Levobunolol?
A: Burning/stinging, itching, blurred vision, eye discomfort, headache, dizziness.
Q3: What are the contraindications for Levobunolol?
A: Asthma, COPD, bradycardia, heart block, cardiac failure, hypersensitivity.
Q4: Does Levobunolol interact with other medications?
A: Yes, it interacts with oral beta-blockers, calcium channel blockers, and digoxin.
Q5: Can Levobunolol be used during pregnancy or breastfeeding?
A: Use with caution. Consult with a specialist. Potential risks to the fetus and nursing infant.
Q6: How does Levobunolol work?
A: It reduces aqueous humor production, thereby lowering IOP.
Q7: How long does it take for Levobunolol to start working?
A: The IOP-lowering effect may take a few weeks to become fully evident.
Q8: What should I do if I miss a dose of Levobunolol?
A: Instill the missed dose as soon as possible and continue with the regular schedule. Don’t double the dose.
Q9: Can Levobunolol be used with other eye drops?
A: Yes, it can be used concomitantly with other IOP-lowering medications if necessary. Maintain appropriate intervals between different eye drops.
Q10: Are there any long-term effects of using Levobunolol?
A: Systemic effects like bradycardia or hypotension are possible with long-term use. Monitor regularly.
